1. Field
Power driven dental scalers are well known. Of particular interest herein is a dental scaler which utilizes compressed air to drive a vibrating element within the scaler.
2. State of the Art
Of the power driven dental scalers currently available, most common are scalers utilizing a flow of compressed air or an electrical ultrasonic transducer to cause a scraping type work tool to vibrate.
Typical of the earlier air-driven dental scalers are those of U.S. Pat. Nos. 3,082,529 and 3,444,622 to Mills et al, which scalers utilize an air-driven ball contained in a chamber. Movement of the ball against the walls of the chamber imparts vibration to the chamber which vibrations are then transmitted to the scraping tool. A more recent type of air-driven scaler, described in U.S. Pat. No. 3,526,962 to Fuerst, utilizes a rotatable mandrel which has an irregularly-shaped tip engaged with a reciprocable block in which the mandrel tip is received.
It is characteristically a problem of these air driven scalers that much of the vibrational energy generated by the vibrator motor is transferred to the handle portion of the dental scaler rather than to the scraper work tool. Moreover, the modes of vibration of these scalers may change as moving parts of the vibration generating mechanism wear with time.
In U.S. Pat. No. 3,703,037 to Robinson, there is described a dental scaler which utilizes an electrical ultrasonic transducer to provide constant modes of vibration for coupling with particular types of work tools. One disadvantage of the ultrasonic scaler, however, is the cost of the transducer and its fairly sophisticated ultrasonic generator.
A recent improvement in air-driven dental scalers is disclosed in U.S. Pat. Re. No. 29,687 to Sertich. This dental scaler has very few moving parts as compared to the aforementioned mechanically complicated air-driven scalers and provides efficient transfer of vibrational energy to a scraping-type work tool with generation of relatively little noise and minimal vibration being transferred to the handle portion of the instrument. Moreover, the Sertich-type scaler provides uniform modes of constant vibration which may be matched with the vibratory modes of various types of work tools without the need for complicated electronic components.
The Sertich-type dental scaler achieves these advantages in part by including a single, rigid vibratable tube mounted on resilient support washers disposed at or near the theoretical vibratory nodes characteristic of the natural vibrational mode of the tube. A work tool, such as a scraper or a pick, is typically secured to the working end of the vibratable tube by a connection between an externally-threaded work tool shank and an internally threaded portion of the tube. Often times it may be difficult to securely attach the work tool to the vibratable tube inasmuch as torque applied to tighten the work tool may result in twisting of the tube within its resilient supports, thus preventing proper and safe attachment of the work tool to the dental instrument. Moreover, even if proper securement of the work tool to the scaler is attained, then excessive torque applied to remove the work tool may result in dislocation or distortion of the resilient supports.
There is, therefore, need for an air-driven dental scaler of the Sertich-type in which proper tightening and loosening of a threaded work tool shank from a resiliently supported vibratable member may be achieved without adversely affecting the resilient supports.